Power-operated wrench



July 28, 1953 G. A. LINUBERG 2,646,966

POWR OPERATED WRENCH Filed Deo. 11, 1951 3 Sheets-Sheet 1 `.J Figi l l:LO i d Vv 8l '52 2@ a2 a4 ze Q3 QLF" L7 a "f3 h. "n ...IU fia is A p 83Si 8,2. i@ 8g 4 a 2O Q5 1V r3 BQ i2 INVENTOR July 28, 1953 A, LINDBERG y2.646,966

POWER OPERATED WRENCH Filed Deo. 11, 1951 v 3 Sheets-Sheet 2 l if d, srlo Fig 6 `rllllllliljglll muli /llO ATTORNEYS July 28, 1953 G. A.LINDBERG 2,646,966

POWER OPERATED WRENCH Filed Dec. 11, 1951 3 sheets-sheet s Il//l/ 32 12571 I ya@ l ma no i3 L'ZL INVENTOR QB GLENN A. Lmmasac BY WFM/mm2#Mm/:Mem

ATTORNEYS Patented July 28, 1953 UNITED STATES PATENT OFFICEPOWER-OPERATED WRENCH Glenn A. Lindberg, Cut Bank, Mont.

Application December 11, 1951, Serial No. 260,991

Claims. (Cl. Z55- 35) This invention relates to power operated Wrenches,and more particularly to a power operated wrench for coupling anduncoupling oil well sucker rods and tubing.

It is among the objects of the invention to provide an improved poweroperated wrench which is readily portable and can be suspended from awell derrick or other supporting structure adjacent a well sucker rod ortubing string while in use; which imparts a series of impacts toa'sucker rod or tubing section engaged thereby to loosen thescrew-thread connection between adjacent rod or tubing sections; whichcan be used to couple or uncouple rod or tube sections by simplyinverting the wrench from one operation to the other; which has meansreleasably holding the wrench in open position for application of thewrench to a rod or tubing section; which holds one tube or rod sectionstationary while applying rotational impacts to an adjacent section; andwhich is simple and durable in construction, economical to manufacture,and positive and effective in operation.

Other objects and advantages will become apparent from a considerationof the following description and the appended claims in conjunction withthe accompanying drawings, wherein:

Figure 1 is a somewhat diagrammatic illustration of a well rig includinga sucker rod and showing in side elevation a power operated wrenchillustrative of the invention suspended from the well derrick andoperatively engaged with the sucker rod;

Figure 2 is a top plan view of the wrench, a portion being broken awayto better illustrate the construction thereof;

Figure 3 is a cross-sectional view on the line 3-3 of Figure 2;

Figure 4 is a fragmentary cross-sectional view on an enlarged scale onthe line 4-4 of Figure 2;

Figure 5 is a fragmentary cross-sectional view on the line 5-5 of Figure3;

Figure 6 is a wiring diagram for the wrench when operated by an electricmotor;

Figure 7 is a side elevational view of a power operated wrench similarto that illustrated in Figures l, 2 and 3, but modied to operate on welltubing rather than sucker rod sections;

Figure 8 is a cross-sectional view on an enlarged scale on the line 8-8of Figure 7;

Figure 9 is a fragmentary cross-sectional View on the line 9 9 of Figure8; and

Figure l0 is a fragmentary cross-sectional view on the line Iii-I0 ofFigure 8.

With continued reference to the drawings, the

well rig illustrated in Figure 1 comprises an oil well derrick I0 ofwell known construction having a cross brace II spaced above the wellplatform l2. A well tubing string I3 extends from the upper end of thecasing I4 through the platform I2 and a sucker rod assembly I5 extendslongitudinally of the tubing string i3 and out of the upper end of thetubing string. The lower end of the sucker rod is connected to an oilpump, not illustrated, in a manner well known to the art, and the upperend of the rod is connected to a rod-reciprocating member, such as awalking beam, also not illustrated, but well known to the art.

The sucker rod I5 comprises a plurality of sections joined together inend-to-end relationship. As is particularly illustrated in Figure 3,each section of the sucker rod has at each end thereof a tapered,screw-threaded portion IB, an annular bead Il at the inner end of thescrew-threaded portion I6, a squared portion I8 at the side of theannular bead I 'I remote from the screwthreaded portion I6, an annularbead I9 at the end of the squared portion I8 remote from the annularbead I1, and the intermediate portion 20 of the rod extends from theannular bead I9 away from the squared portion I8 and is usually ofcircular cross-sectional shape. Two adjacent rod sections are coupledtogether in end-to-end relationship by having the screw-threadedportions I6 at their adjacent ends threaded into the respectivelyopposite ends of a coupling sleeve or collar 2| which is slightlyinwardly tapered from each end and provided in each end withscrew-threads engaging the screw-threads on the end portions of the rodsections. The sections of the well tubing I3 are provided with externalscrew-threads at each end and are secured together by having theiradjacent ends threaded intl) the respectively opposite ends ofinternally screw-threaded coupling sleeves or collars 22, as isparticularly illustrated in Figure '7.

In the case of both the sucker rod sections and the well tubingsections, two adjacent sections are threaded into the associatedcoupling collar by rotating the sections in respectively oppositedirections or by holding one section stationary while rotating the otherand are uncoupled in the same manner by reversely rotating the movablesection.

As the construction of well rigs including the well tubing or flow pipeand the pump sucker rod is Well known to the art and constitute no partof the present invention, it is considered that a more detailedillustration and description 3 of the well rig is unnecessary for thepurposes of the present disclosure.

The present invention is primarily concerned with a power operatedwrench for coupling and uncoupling sucker rod or well tubing sections,and such a wrench has been shown in two slightly modified arrangementsin the accompanying drawings.

The wrench illustrated in Figures 1 to 6, inclusive, comprises a flat,hollow housing 25 of somewhat elliptical shape having top and bottomwalls 25 and 21 disposed in spaced apart and substantially parallelrelationship to each other, and a side wall 28 having arcuately roundedend portions of substantially semicircular extent and straight sideportions interconnecting theiends of the arcuately curved end portions.l

Bearings rings 30 and 3l are disposed against the inner side of the topwall 25 and bottom wall 21 of the housing, respectively, substantiallyconcentric with the center of Vcurvature of one end of the side wall 28of the housing anda main gear 32 is disposed between and journaled onthese bearing rings for rotation in the housing. This gear 32 has acentrally located bore or aperture 33 provided with longitudinallyextending splines or serrations, and has a notch 34 extending from theaperture 33 to the periphery of the gear. The notch 34 has substantiallyparallel side surfaces spaced 'apart a distance slightly greater thanthe thickness of the squared portions I8 of the sucker rod,"these sidesurfaces being outwardly inclined near the periphery of the gear, as isparticularly illustrated in Figure 2, to facilitate passing of thesquared portions of sucker rods into'the notch in the gear.

A jaw element 35 having longitudinally extending serrations or splineson its outer surface and of Igenerally cylindrical shape is' insertedinto the bore 33 of the gear 32 and has a notch 36 therein ofsubstantially the same size and shape as the size and shape of thecross-sectional area of the squared portion I8 of the sucker rod.

The insert jaw 35 has at its end adjacent the bottom wall 21 of thehousing an outwardly'extending annular flange 38 which closely fits theinner edge of the bottom bearing ring 3l.

The top wall 26 of the housing is detachably secured to the side wallbysuitable means, such as the screws 39, extending vthrough apertures inthe marginal portion of the top wall and threaded into tapped holes inthe top edge of the side wall, so that the gear 32 can be'removed fromthe housing upon removal of the top wall 26. The insert 35 can beremoved from the gear when the latter is removed from the housing, anddifferent inserts may be placed in the gear to accommodate the wrench tovarying sizes of the squared portions of sucker rods.

The top and bottom vwalls 26 and 21 of the housing are provided withnotches 40 and 4! which are in alignment withe'ach'other and registerwith the notch 34` in the gear 32 when the gear is in a predeterminedrotational posi tion relative to the housing, 'as illustrated in Figure2, and the side wall 28 is provided with an opening 42 in alignment withthe outer ends of the notches 40 and 4| in the top`an`d bottom walls ofthe housing.

Idler gears 43 and 44 are journaled in the housing between the gear 32and the end of the housing remote from the opening 42, and these idlergears mesh with the main gear 32 at spaced apart locations around themain gear, the distance between the locationshatwh-ichthe idler gearsmesh with the main gear being greater than the width of the outer end ofthe slot 34 in the main gear, so that at least one of the idler gearswill always be in mesh with the peripheral teeth on the main gear 32.

A screw shaft 45 extends through apertures 4G and 41 in the top andbottom walls 216 and 21 of the housing, which apertures aresubstantially concentric with the center of curvature of the end of theside wall 28. of the housing remote from the main gear 32.

.In the arrangement illustrated, an electric motor 5B is secured at oneend to the bottom wall 21 of the housing 25 and the motor housing has inits end wall 53 adjacent the bottom wall of the housing an opening 5lregistering with the opening 41 in the bottom wall 21. The screw shaft45 is connected at one end to the adjacent end of the shaft of the motor50, or, if desired, may be made continuous with the motor shaft andjournaled in the housing of the electric motor.

A stop collar 52 is provided on the screw shaft 45 one at the endthereof remote from the motor.

Outwardly of the stop collar 52 the screw shaft is provided with anarbor 54 of reduced diameter journaled in a bearing 55 supported in theouter end of a hood-shaped brace 55 which extends transversely of thethickness of the housing 25 and is joined at its other end to thehousing of the motor 55 at the end of the motor housing adjacent thewrench-housing 25. v

A drive gear 51, having a screw-threaded bore extending coaxiallytherethrough, is threaded onto the screw shaft 45 and meshes with bothof the idler gears 43 and 44. This gear 51 is movable longitudinallyrelative to the idler gears 43 and 44, and remains in mesh with thesegears at all times. f

A U-shaped handle 69 is connected at one end to the side wall 28 of thehousing 25 and is connected at its other end to the housing of the motor55, and switches 6l Vand 62 are mounted in the handle 55 in tandemrelationship to each other and connected to the motor 50 by conduits, asindicated at 63. A grip lever 64 is pivotally mounted at one end in thehandle 60 at the end of the handle remote from switches 5l' and 62 andcarries at its end adjacent the switches a projectionor dog 65 forsuccessively operating the switches 'BI and 62 when the grip member ismoved toward -the 'intermediate portion of the handle. A compressionspring 65, disposedbe'- tween the intermediate portion of the handle 60and-the grip member 64, resilicntly urges the grip member away from theintermediate portion ofthe handle and4 to'a non-operating positionrelative to the switches GI and 62, the switches being operatedloymanually moving the grip member toward the intermediate portion of thehandle against the force of the spring 66.

Power is supplied to the motor through a suitable extension cord 61, andit is to be understood that while an electric -motor has beenillustrated and hereinabove described for operating the wrench, ahydraulic or pneumatic motor of known con-struction may be substitutedAfor the electric'frnotorgif' desired, withut'in any va'y'e'x-l ceedingthe scope of the invention.

With the arrangement illustrated, when one of the switches El or 62 isclosed to energize the m-otor 5D, the screw shaft 45 will be rotated,and the gear-51 will be threaded outwardly along the screw shaft untilit strikes the'stop collar 52. This sudden -termination :ofI relativelmovement between the gear and the screw shaft causes the inertia of therotatable armature of the motor 50 to deliver an impact to the gear 51and from this gear through the idler gears 43 and 44 to the main gear32. As soon as the impact has been delivered to the main gear 32, thegrip member 64 is released to open the motor controlling switch anddiscontinue the application of power from the motor to the wrench gears.The gear 51 is provided at its end adjacent the motor 50 with an annulargroove |59 in a skirt portion of the gear and an annular collar |5| hasat one end an inwardly directed annular flange |52 rotatably received inthe groove |58 in gear 51 and at its other end an annular externalgroove |53.

A coiled tension spring |54 surrounds the motor shaft and has one endcoil secured in the groove |53 of collar |5| and its other end coilsecured in an annular external groove |55 inA a second collar |56secured on motor shaft 45 at a location spaced along the shaft fromcollar l5 I.

If the main gear 32 is engaged with an object to be rotated, such as awell sucker rod, and this object is not substantially rotated by thefirst impact delivered to the main gear 32 incident to the impact of thegear 51 against the stop collar 52, upon release of the grip member l64to open the motor controlling switch, spring |54, which is stretchedwhen gear 51 moves lalong shaft 45 to stop collar 52, contracts andreturns gear 51 along shaft 45 to the end of the screw-threaded portionof this 'shaft adjacent the motor 50. If the motor controlling switch isnow reclosed, a second impact will be delivered to the gear 32 and theimpacts may be repeated until the sucker rod joint is freed and theportion of the sucker rod engaged in the main gear 32 caused to rotate.As soon as the joint has been freed, the motor controlling switch may bemaintained closed until the sucker rod joint has been completelyunthreaded. Y

A bracket 18 is secured to or formed integrall with the bottom wall 21of the housing, and projects laterally f-rom the housing intermediatethe length o'f lone of the straight portions of the side Wall 28. A post1| of noncircular and preferably square cross-sectional shape extendsthrough the bracket and is secured to the bracket ,adjacent themid-length location of the post, the post being formed integrally withthe bracket, if desired.

The post 1| is disposed substantially perpendicular to the planes of thetop and bottom walls of the housing 25, and a back-up wrench 12 isdetachably secured at one end to the post 1| 'and is provided at itsother end With spaced apart jaws which receive a squared portion I8 ofthe sucker rod adjacent the squared portion received in the main gear 32of the french, so that, when an upper sucker rod section is being turnedby the wrench to couple or uncouple it 'from the vadjacent lowersection, the lower section is held against rotational movement by theback-up wrench 12.

In the arrangement illustrated, the back-up wrench 12 is provided at itsend adjacent-the post 1| with an eye formation 13 having a square holetherein through which the post extends and is provided with a springpressed ball detent -a'ssembly 14 which engages in a depression, asindicated at15, in the post to releasably secure the back-up wrench inoperative position on the post 1|.

Lugs 16 'and 11 are provided on side wall 28 of the housing, and arealigned transversely of the 6 housing near the end of the latter towhich the' handle is attached. A U-shaped lbail 18 is pivotallyconnected at its ends to lugs 16 andY 11 and a coil tension spring 19 isconnected at one end to bail 18 -at the end of the bail remote fromhousing 25 and is connected at its other end to a hook which is adaptedto engage a support. such as the crossbar of well derrick I9, to suspendthe wrench in operative position adjacent the sucker rod of the well.

Handle sockets 8| and 82 are provided on the upper side of the top wall26 of the housing one -at each side of the latter, and open to theopposite side of the housing adjacent the mid-length location thereof.Handles 83 and 84 are secured each at one end in the sockets 8| and 82,respectively, and project outwardly from the respectively opposite sidesof the housing substantially perpendicular to the longitudinal centerlino of the housing.

With this arrangement, the wrench can be used in its upright position,as illustrated in Figure 3, for uncoupling adjacent sucker rod sectionsand can be inverted in the bail 18 and used in its inverted position forcoupling adjacent sucker rod sections as a sucker rod is being run inthe well.

A dome-shaped cover 9| is secured to the top wall 26 of the housing incovering relationship to the opening 46 and the bearing 55 to protectthe gears from dust and other foreign matter.

When the wrench is inverted, the back-up component 12 is, of course,moved from one end to the other end of the post 1|, so that it willprovide the same function in the inverted as in the upright position ofthe wrench.

A small solenoid 85 is mounted on the top wall 26 of the housing 25above themain gear 32 and has a movable armature 86 projecting throughregistering apertures in the top wall 26 of the housing andthe upperbearing ring 38 and provided with a rounded end 81. The gear 32 isprovided with a rounded depression at a Ilocation therearound, such thatwhen the rounded end of the armature 86 is in the rounded depression inthe gear, the gear is releasably held in a rotational position in thehousing, such that the notch 34 in the gear registers with the openings39, 4U and 4| in the top, bottom and side walls of the housing. -Acompression spring 88 surrounds the armature 86 between the bottom endof the solenoid coil 89 and an abutment washer 98 secured on thearmature to resiliently urge the armature into engagement in thedepression in the gear and the coil 89 of the solenoid is connectedthrough the switches 6| and 62 with the energizing circuit for the motor50 so that the armature of the solenoid is automatically moved out ofengagement with the gear 32 whenever the motor is energized. A manuallyreleasable latch may be substituted for the solenoid operated latch, asdescribed above, without in any way exceeding the scope of theinvention.

A wiring diagram for the motor and the solenoid 85 is illustrated inFigure 6, and includes a source of electrical energy, such as a batteryor auto transformer 92 and relay switches 93 and 94 in addition to themanually operated switches 8| and 62, the solenoid 85 and the motor 50.

The motor 50 is connected at one side to one end of the battery 92 by aconductor 95, and is connected at its other side by a conductor 96 toone contact 91 of the relay switch 93 and to one-contact 98 of the relayswitch 94. The

gemiste (other bontactt?! -fofetheerelay s witc'zl'ia 93::isco'rilnectedlaby aV conductor -to the 'otherfendfof theI batter-y 92,and the -Other1contact--|0| |`of 'the relay switch 94 isconnectedftofthefbattery v92 between the ends ofthe batteryby-aiconduc'-tor |02, so thatfwhen the'lrelayi-switch?93-f is closed, the Amotor isoperated at -Ifull-sipeedand when the relay switch .gfiisclosedgthemotor is operated at a slow speed.

The coils |03 and |04-o'f AtheI` relay switchesj93 and S4.are bothconnected, each' at-one-end,by aconductor to theV conductor-|00 andatheend of the. batteryremote from that to-which the motor is connected bythe=conductor195. The

`other `end-of the coil |03 is connected by coni ductors |05 and |01 vtoone'contactla of the manually operated switch 6I, the other contact |09of which is connected by a conductor ||0 to the conductor 95, so that,when the switch 6| is closed, the coil |03 will be energized to closethe relay switch 93. The other end of the coil |04 of the relay switch94 is connected by a conductor to one contact ||2 of the manuallyoperated switch 62 and the other contact ||3 of this switch is connectedby a conductor ||4 to the conductor 95, so that when the switch 62 isclosed, the coil |04 will be energized, closing the relay switch 94.

The solenoid 85 is connected between the conductors |05 and |01 inparallel with the relay Y switch coil |03, so that it will be energizedwhenever the relay switch 93 is closed.

With this arrangement, the motor can be operated at full speed or at lowspeed by selectively closing the manually operated switches 6| and 62.

In the modied form of the arrangement illustrated in Figures 7 to 10,inclusive, the construction of the wrench is the same as that describedabove, except that the main gear 32 and the back-up wrench 12 aremodified to engage tube sections instead of the sucker rod sectionsillustrated and described in connection with the form of the wrenchshown in Figures l to 6, inclusive.

In the modified arrangement, the main gear 32' is provided with acentral aperture |20 and a notch |2| leading from this central apertureto the periphery of the gear, the central aperture having asemicylindrical shape at the inner end of the notch, and the notchhaving a width somewhat greater than the outside diameter of the tubesections to be received therein.

The gear 32 is provided in the central aperture thereof with angularlyspaced apart, longitudinally extending notches and tube-engagingelements |22 of rectangular cross-sectional shape are seated one in eachof these notches and secured to the gear. At one side of the notch |2|the gear is provided with a recess |24 and a dog |25 is pivotallymounted in the recess |24 and has a partly cylindrical surface |26facing the opening in the gear and provided with a longitudinallyextending groove receiving a tube-engaging element |21 of rectangularcrosssectional shape. The dog includes a finger portion |28 extendingfrom the tube-engaging element |21 into the notch |2| and provided nearits distal end with a tapped hole receiving a set screw |29 which isadapted to bear against the outer surface of a tube section I9 receivedin the wrench to limit the pressure between the tube-engaging elements|22 and |21 and the tube.

A leaf spring |30 is disposed within the recess 24 and engaged betweenthe gear and the dos 'Il it tdresinenuy urge the 'dog into v'engagementwith a tubesection |-3- received in the gear, and aiballdetent |3| ismounted in the gear at foriejehd of the rec'essv |24 and engages thedistalendf of the-fingerportion |20 of the dog to .in retractedposition'andthe wrench is then 'nivedintoengagement with a tube section adjacenta connecting sleeve or collar 22 on the tube "stringi" the tube sectionmoves into the open'- "ing'irr the gear; it tripsthe dog |25, so thatthe dog moves away from the ball detent |3| and the set screw |29approaches the outer surface of the tube section, thetube-engagingelements |22 and |21 being brought into rm engagement with the outersurface of the tube section. Now, as the gear 32 is rotated, the element|21 is moved slightly toward the tube section, forcing the element andthe element 22 to bite into the outer surface of the tube 'section andprovide a firm grip between the gear and the tube section, this bitingaction 4being limited by Contact of the set screw |29 with the outersurface of the tube section.

The back-up wrench 12 of this form of the invention has at its endremote from the post 1| a jaw formation |33 shaped to receive a tubesection |3 therein, and engages a tube string adjacent the lower end ofa connecting collar 22 when the gear 32 engages the tube string adjacentthe upper end of such a collar.

The jaw formation |33 of the back-up wrench 12 has a partly cylindricalinner surface and an opening through which the tube section enters thejaw formation and is provided in its inner surface with groovesextending longitudinally of the inner surface at angularly spaced apartlocations. Tube section-engaging elements |34 of square or rectangularcross-sectional shape are mounted one in each of these grooves andsecured to the jaw formation |33 in a manner to present a sharp edge forengagement with the outer surface of the tube section I3.

A dog |35 is pivotally mounted on the jaw formation |33`at one end ofthe latter by a pivot pin |36 and carries a tube-engaging element |31similar'to the elements |34. At its distal end the dog |35 carries a setscrew |38 which is engageable with the outer surface of a tube sectionreceived in the jaw formation |33 to limit the pressure between theelements |34 and |31 and an associated tube section, and a leaf spring|40 is mounted on the jaw formation 33 adjacent the pivot pin |36 andengages the dog |35 to urge the latter toward a tube section I3 receivedin the jaw formation.

In this case, the dog |35 is releasably latched in retracted position bya ball detent |4| carried by the dog and engageable in a recess |42provided in the portion of the jaw formation |33 to which the dog ispivoted, this latch being released by the pressure of the tube sectionagainst the inner end portion of the dog as a tube section is insertedinto the jaw formation |33 of the backup wrench component. As the gear32' tends to turn one of the sections of the tube spring, the back-upwrench 12' engaging the adjacent section holds such adjacent sectionagainst rotation, so that the coupling between the two adjacent sectionscan be threaded together or apart, depending on the position of thewrench.

Various modifications of the wrench, such as increasing or decreasingthe weight and strength thereof, providing a reduction gear between themotor and the screw shaft and modifying the wiring circuit to provideonly a slow speed ofperation, may be made, if desired, without in anyway exceeding the scope of the invention.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are, therefore, to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are, therefore, intended to be embracedtherein.

What is claimed is:

1. A power operated wrench comprising a housing, a rst gear rotatablymounted in said housing and having a radially disposed notch extendingfrom the periphery to the center thereof for receiving an object to beturned by said wrench, said housing having an opening thereinregistering with the notch in said gear when said gear is in apredetermined rotational position relative to said housing, idler gearsrotatably mounted in said housing and meshing with said rst gear atspaced apart locations therearound, a second gear disposed in saidhousing and meshing with said idler gears, said second gear having ascrewthreaded bore extending coaxially therethrough and beinglongitudinally movable relative to said idler gears, a screw shaftjournaled in said housing and threaded through the bore of said secondgear, a stop on said screw shaft limiting movements of said second gearlongitudinally thereof, and a motor mounted on said housing anddrivingly connected to said screw Shaft, said second gear being movablealong said screw shaft from said motor to said stop to deliver an impactthrough said idler gears to said first gear when it engages said stop,and spring means connected to said second gear moving the latter awayfrom said stop after delivery of the impact.

2. A power operated wrench comprising a housing, a, flrst gear rotatablymounted in said housing and having a radially disposed notch extendingfrom the periphery to the center thereof for receiving an object to beturned by said wrench, said housing having an opening thereinregistering with the notch in said gear when said gear is in apredetermined rotational position relative to said housing, idler gearsrotatably mounted in said housing and meshing with first gear at spacedapart locations therearound, a second gear disposed in said housing andmeshing with said idler gears, said second gear having a screw-threadedbore extending coaxially therethrough and being longitudinally movablerelative to said idler gears, a screw shaft journaled in said housingand threaded through the bore of said second gear, a, stop on said screwshaft limiting movements of said second gear longitudinally thereof, amotor mounted on said housing and drivingly connected to said screwshaft, said second gear being movable along said screw shaft from saidmotor to said stop to deliver an impact through said idler gears to saidfirst gear when it engages said stop and being movable from said stopafter delivery of the impact, and means mounted on said housing andengaging sai-d first gear releasably latching the latter in a rotationalposition relative to said l0 housing such that the notch in said rstgear is in registry with the opening in said housing.

3. A power operated wrench comprising a housing, a main gear rotatablymounted in said housing and having a radially disposed notch extendingfrom the periphery to the center thereof for receiving .an object to beturned by said wrench, said housing having an opening thereinregistering with the notch in said gear when said gear is in apredetermined rotational position relative to said housing, a motormounted on said housing, means in said housing connecting said motor tosaid main gear and effective to deliver rotational impacts to said maingear upon operation of said motor, a post mounted on said housing andextending to respectively opposite sides of the latter, and a back-upwrench detachably mounted on said post-and engageable with an object ata location spaced from said first gear to hold the object engagedthereby stationary while the object engaged by said rst gear is rotatedrelative to the object engaged by said backup wrench, said back-upwrench being selectively mountable on said post adjacent either end ofthe latter.

4. A power operated wrench comprising a housing, a main gear rotatablymounted in said housing and having a radially disposed notch extendingfrom the periphery to the center thereof for receiving an object to beturned by said wrench, said housing having an opening thereinregistering with the notch in said gear when said gear is in apredetermined rotational position relative to said housing, a motormounted on said housing, means in said housing drivingly connecting saidmotor to said main gear and imparting rotational impacts to said maingear upon operation of said motor, said main gear having a cavitytherein opening into said notch,

i at least one work engaging element mounted on said main gear andpresenting a sharp edge directed inwardly of said notch within the innerend portion of said notch at a location spaced from said cavity, a dogpivotally mounted on said gear within said cavity and at one side ofsaid notch and having a finger extending into the notch in said gear, awork piece-engaging element mounted in said dog and presenting a sharpedge at the side of said dog adjacent the notch in said gear, a springconnected between said dog and said gear resiliently urging said doginwardly of said notch, and a set screw carried by said dog adjacent thedistal end of the finger thereof for engaging a work piece extendingthrough said notch and engaged by said work piece engaging elements tolimit the pressure between said work piece-engaging elements and thework piece engaged thereby.

power operated wrench comprising a housing, a main gear rotatablymounted in said housing and having a radially disposed notch extendingfrom the periphery to the center thereof for receiving an object to beturned by said wrench, said housing having an opening thereinregistering with the notch in said gear when said gear is in apredetermined rotational position relative to said housing, a motormounted on said housing, means said housing drivingly connecting saidmotor to said main gear and imparting rotational impacts to said maingear upon operation of said motor, a post mounted on said housing andextending to respectively opposite sides of the latter, and a back-upwrench detachably mounted on said post and engageable with an object ata location spaced from said main gear to hold the object engaged therebystationary whilethe object said post adjacent either end of thelatterand 5` having at its end remote from said post a rounded jaw formationadapted to receive a Work piece of circular cross-sectional shape andhaving at least one Work piece-engaging element mounted therein andpresenting a sharp edge Within said jaw formation, a dog pivotallymounted on said. backup wrench at the outer end of one side of said jawformation, a work piece-engaging element carried by said dog andpresenting a sharp edge inwardly of said jaw formation, a springconnected between said jaw formation and said dog resiliently urgingsaid dog in a direction to engage the work piece-engaging elementcarried thereby with a work piece received in said jaw formation, and aset screw carried by said dog and engageable with a work piece in saidjaw formation to llimit the pressure betWeensaidwork' piece-engagingelements, and a work piece engaged thereby.

GLENN A. LINDBERG.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Datev 1,300,995 Moody Apr. 15, 1919 1,820,545 Smith Aug. 25, 19311,831,259 Peterson et a1 Nov. 10, 1931 2,000,221 Dawson May '7, 19352,425,793 Fosnot Aug. 19, 1947 2,514,914 Van Sittert Julyll, 19502,550,045 De Hetre Apr. 24, 1951 2,556,536 Harris June 12, 19512,566,561 Edelberg Sept. 4, 1951 2,566,999 Stone Sept. 4, 1951 2,573,212Martois Oct. 30, 1951 2,624,550

Lundeen Jan. 6, 1953

